and commissioner davis was quite firm about that. and i think they both did themselves a great service and the city a great service by being as definitive in pfotenhauer cases as they are. this is so far been a very locked down investigation. very little leaking. there's talk now about finding photographs before the event and whether or not the security along boylston street was at tight as it should be. >> charlie, i want to just jump in for a second so the viewers can see on the left is live images of the candle light vigil being held in dor chester moments ago, not live, for the 8-year-old victim of the bombings yesterday. martin richard. there is a candlelight vigil being held in his neighborhood of dorchester and tons of people out for that. from washington, we have nbc news justice correspondent, pete williams. thank you so much for being with us. it to get to the investigation and what we know, the latest on that, but first, i want to begin with these ricin reports. a letter sent to roger wicker did test positive. how serious